Can lightning help predict tornadoes? A D.C. area case may shed some light

Lightning strikes near a violent tornado in Kansas on April 14, 2012. Photo by Greg Johnson of TornadoHunter.com.

A sudden surge in lightning activity along with wild fluctuations in a storm’s electric field may help predict tornado formation a local researcher has found.

A serendipitous encounter with a tornado near Greenbelt, Md. on June 1 this year led to this finding says Johns Hopkins University geophysicist Benjamin Barnum, who presented this work at this week’s annual American Geophysical Union fall meeting.

(In addition to their own sensors, Barnum and his team are also analyzing data from the National Lightning Detection Network, the U.S. Precision Lightning Network, the World Wide Lightning Location Network and the D.C. Lightning Mapping Array (DCLMA), a local network of 10 sensors.)

Barnum told me this was atypical and that, “the rapid increase in lightning rates measured by the single point systems ... were nearly double or triple what we usually measured during other thunderstorms during this spring.”

He also notes, “the lightning activity/rates decreased rapidly after 7 p.m., and the tornado was spotted at Greenbelt at 7:06 p.m.”

A March 2, 2012 storm in Alabama is shown through cross section reflectivity, its lightning flash rate and change in flash rate (DFRDT). Lightning is seen spiking in advance of severe weather and a tornado. Source PDF.

Another recent example case occurred on March 2, 2012. Forecasters at NWS Huntsville, Alabama noticed an increase in lightning on a developing storm. This fact helped push them to issue a warning. In the 20 minutes thereafter, severe weather reports trickled in, including a confirmed tornado.

However, many scientists heavily involved in lightning and severe weather research point out that a “lightning jump” (quick and intense increase of lightning) cannot discern severe weather types. Rather, lightning jump can indicate the updraft (and hence the storm itself) is strengthening.

In essence, this technique of lightning data monitoring can help to “tip the scale” on whether or not to issue a severe warning.

What made the June 1 D.C. area event unique, from Barnum’s point of view, is that there were extraordinarily quick changes in the electrical field of the storm, something he refers to as “rapid oscillations in the vertical fields.”

“The electric field oscillations were quite different from the types of electric field changes we measure from regular lightning strikes,” Barnum said.

The fluctuations end as the tornado develops.

Electric Field Mill image from AGU poster: Case Study of Severe Lightning Activity Prior to and During the Outbreak of the June 1st Greenbelt Tornado. By Ben Barnum, Surjit Badesha, Ali-Reza Shishineh, Norman Adams (Johns Hopkins Applied Physics Lab)Barnum is quick to admit that these phenomena are not always observed with such events. He also points out this is the first time he has measured a tornado so close to the JHU/APL sensors.

Zac Flamig, a Ph.D student in meteorology at the University of Oklahoma, who guided me to some of the better literature on the larger subject, is also understandably cautious.

Flamig says that from what he has seen in his research, he does not “believe increased lightning activity can differentiate a storm strengthening non-tornadically vs. one strengthening tornadically.”

He reminds us, “there are cases where severe weather occurred with a complete lack of lightning.” Still, Flamig points out that a better understanding of lightning’s relationship to the larger storm will provide a more complete picture for operational meteorologists.

Regardless of any qualifications, Barnum’s findings appear ripe to feed more data into the research of lightning and its potential signal for tornadic activity. As anyone in the field will tell you, the more early warning of any severe weather, the better.

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Comments our editors find particularly useful or relevant are displayed in Top Comments, as are comments by users with these badges: . Replies to those posts appear here, as well as posts by staff writers.